The big snooze: Mysteries of wildlife hibernation
Ever wished you could fall asleep and not wake up for three months?
Here’s what would have to happen to make that possible: You would have to store fat, suppress your heart rate and metabolic system, overcome the necessity to urinate, quell the need to eat and be able to survive freezing temperatures down to 22 degrees.
A great assortment of creatures from mammals, including bats, bears, hedgehogs, Madagascar lemurs, variety of rodents, marsupials and ground squirrels; to fish, butterflies and reptiles hibernate for many months, while others, like birds, may temporarily fall into a state of torpor to survive ice and snow storms.
Goldfish and koi in winter ponds also fall into torpor once water temperatures reach around 35 degrees.
For most animals, the big snooze is a survival method brought on by low temperatures and lack of food.
“Hibernation is an adaptation to an anticipation of famine,” said Brian Barnes in a National Wildlife Federation article. Barnes is director of the Institute of Arctic Biology at the University of Alaska–Fairbanks. During hibernation, he explained, an animal must “manipulate every cell’s need for energy and oxygen, plus reduce heat production.”
Writing in NWF, Roger Di Selvestro points out how the Arctic ground squirrel is considered the champion hibernator of all time since it survives in one of the severest environments imaginable by essentially sleeping nine months out of the year. “It can survive for three weeks at a body temperature of 22 degrees F, a condition that would kill more southerly rodent hibernators in less than an hour.”
However, experts say there are two types of hibernation; facultative and obligate.
Facultative hibernators sleep only in response to lowered temperatures or food scarcity, while obligate hibernators spontaneously go to sleep every year regardless of temperature of food supply.
For example, there are two genetically similar species of prairie dogs in different territories that fall into separate hibernation categories; the white-tailed prairie dog is an obligate hibernator and the black-tailed prairie dog is a facultative hibernator that in some instances may not hibernate at all.
The mystery surrounding physiological occurrences during hibernation has scientists interested in what lessons could be learned to help humans with medical ailments such as osteoporosis.
Researchers are interested in knowing why such long periods of inactivity during hibernation result in no loss in bone, muscle mass or strength, whereas a non-hibernating creature would start losing significant bone and muscle mass after 4 to 17 weeks of sleep or lack of activity.
Wildlife conservationists warn that study of the subject is fine as long as no animals are harmed or injured during the process.
To watch a cute hazelnut dormouse fattening up for winter hibernation click here.
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